This invention relates to a stent introduced into a vessel, such as a blood vessel, lymph vessel, bile duct or ureter for maintaining the shape of the vessel. More particularly, it relates to a luminal stent attached to a site of angioplasty after the operation of percutaneous angioplasty of a stenotic part of the blood vessel, such as artery (the operation of introducing a balloon forming portion annexed to the end of a catheter into a constricted portion of the blood vessel for forming a ballooning for dilating the constricted portion for improving blood flow) and a device for attaching the luminal stent.
As this type of the luminal stent, there is known a tubular stent constituted by wrapping a meshed structure formed by intertwining longitudinal and transverse wires of e.g. stainless steel. Such tubular stent is introduced into the site of angioplasty and dilated there so as to be attached thereto.
This known type of the stent however suffers from the problems that it is hard and tends to stress the vessel to produce inflammation or hypertrophy in the vessel which may cause reconstriction in the vessel, and that the stent is semipermanently left as a foreign matter within the living body, which is inherently not desirable to the living body.
If the metal stent, which is left in the vessel semi-permanently or for a time longer than is necessary, is attached within the vessel, it may occur that the stent turns out to be a kind of a nucleus and the risk is high that stenosis be again caused in the site of attachment of the stent. Besides, an injury done to the vessel around the stent tends to cause abnormal multiplication of living cells on the inner wall of the vessel to contract the vessel.
It is therefore an object of the present invention to provide a luminal stent free from these problems and a device for attachment of the stent.
According to the present invention, the above object is accomplished by a luminal stent consisting of a tubular member produced by knitting a bioresorbable polymer yarn, and a luminal stent attachment device comprising the luminal stent which is fitted over a balloon forming portion in the vicinity of a distal end of a catheter.
The bioresorbable polymers may be enumerated by polylactic acid(PLA), polyglycolic acid(PGA), polyglactin (PGA-PLA copolymer), polydioxanone, polyglyconate (copolymer of trimethylene carbonate and glycolide) and a copolymer of polyglycolic acid or polylactic acid with ∈-caprolactone.
The bioresorbable polymer may be admixed with a variety of materials, including pharmaceuticals. The materials may also be deposited on the fiber surface.
The luminal stent of the present invention is introduced into and attached to the site of angioplasty by a catheter fitted with a balloon and attached in place by dilating the balloon. The luminal stent may retain its shape for several weeks to several months after attachment and disappears in several months after attachment by being absorbed in the living tissue after lapse of several months after attachment.
If an X-ray impermeable agent is admixed in the bioresorbable polymer, the state of the luminal stent may be observed after attachment by irradiation of X-rays from outside.